The migrant crisis in Europe seems to be shaking the foundations of civil order on the most popular overseas continent for American travelers. The crisis created by refugees fleeing en masse the destruction of their homes in Syria and Iraq is threatening one of the basic principles underlying the establishment of the new, united Europe: free movement across national borders.

Tour operators, who are by definition relegated to the front lines of travel operation, are inevitably among the first responders to any crisis anywhere that may affect travelers. TravelPulse reached out to some of the top operators of tours and travel in Europe for a front-line report on how the crisis is affecting travel in Europe.

On the home front, tour operators are receiving inquiries from clients who are preparing to visit Europe and are wondering if the crisis will affect their trips.

"We have received several calls from our travelers as Mayflower has river cruises on the Danube operating at this time,” said John Stachnik, president of Mayflower Tours. “After reassuring them that we do not go to areas impacted by the migration, and that we have a Business Manager on each of our sailings who can change events at any point, the travelers were assured, and we received no cancellations. Since we exclusively charter all of our river vessels, we exercise greater control over events. The traveler trusts us to do the right thing, and we certainly will.”

In Europe itself, tour operators have the advantage of having close connections with networks of people on the ground in the destinations where they operate. They can get information quickly, at the earliest signs of problems, and they are used to handling the logistics of travel and the adjustments that periodically must be made to adapt to changes and problems.

“Since we have our own team in Budapest, we’ve been able to switch from rail to road on route to Vienna as required,” said Robert Drumm, president of Alexander + Roberts. “Beyond that manageable change, we’ve had no disruption to our current operations.”

“The influx of migrants into Budapest, specifically, has caused interruptions in local and regional train service,” said Steve Born, vice president of marketing of the Globus family of brands. “We have had Monograms guests in the region and while they have not faced any safety concerns, we have made alternate arrangements for them to travel by coach instead of train when going from Budapest to Vienna. Other than that minor transportation shift – and monitoring the situation very closely, of course – it has been business as usual for Globus, Cosmos and Monograms throughout Europe.”

More from TravelPulse

A New Way to Experience NYC

5 Ways to Experience Australia's Top End

The Hottest Trend in Air Travel? Yoga

5 Pro Tips on How to Make Great Photographs on the Rocky Mountaineer

Unique Ways to Explore Uluru (Ayers Rock)